Transition metals

Chemical cells produce a voltage.

A chemical cell can be made by placing the metals copper and iron in a beaker of sodium chloride solution as shown in Figure 1.

Describe what will happen to the reading on the voltmeter over a long period of time.

Iron is a transition metal.

Which of the following is most likely to be a property of iron?

An iron atom has a diameter of 2.5210^–10 m.

What is the size of this iron atom in nanometres?

Figure 2 shows the arrangement of atoms in three different alloys of copper and

Explain which of the three alloys, A, B and C, is the strongest.

There are several stages to the production of sulfuric acid in industry.

Sulfur dioxide is required for the production of sulfuric acid.

Sulfur dioxide can be obtained by heating copper sulfide, Cu₂S, in excess air.

Calculate the atom economy for the production of sulfur dioxide, SO₂, in this reaction.

(relative atomic mass: Cu = 63.5 relative formula masses: O₂ = 32.0, Cu₂S = 159.0, SO₂ = 64.0)

Give your answer to two significant figures.

atom economy =_........

In one stage vanadium oxide, V₂O₅, is used.

Based on the position of vanadium in the periodic table, which row shows the most likely melting point of vanadium and colour of vanadium oxide?

The equation shows a reaction forming sulfuric acid.

Calculate the maximum mass of sulfuric acid that could be produced from 400 tonnes of sulfur trioxide, SO₃.

(relative formula masses: SO₃ = 80, H₂SO₄ = 98)

maximum mass of sulfuric acid =_........ tonnes

Using a different amount of sulfur trioxide, it was calculated that 700 tonnes of sulfuric acid could be made.

The actual mass produced was 672 tonnes.

Calculate the percentage yield of sulfuric acid.

percentage yield =_........

State two reasons why the percentage yield is less than 100 %.

Chemical cells produce a voltage.

A chemical cell can be made by placing the metals copper and zinc in a beaker of sodium chloride solution.

Figure 1 shows a diagram of this chemical cell.

Describe what will happen to the brightness of the light bulb over a long period of time.

Copper is a transition metal.

Which of the following is most likely to be a property of copper?

A copper atom has a diameter of 0.256 nm.

What is the size of this copper atom in metres?

Brass is an alloy of copper and zinc. One type of brass contains 70% copper.

Zinc atoms are slightly larger than copper atoms.

Draw a labelled diagram in the box to show the arrangement of copper and zinc atoms in this alloy.

Use the circle in the box as a guide to the size of a copper atom.

Transition metals have many uses.

The pie chart in Figure 6 shows the uses of one transition metal.

Calculate the percentage of this transition metal used in construction.

percentage of this transition metal used in construction =_........

Figure 7 shows five statements about iron.

Put ticks () in the boxes in Figure 7 to show which statements are true and which statements are false. The first one has been done for you.

Most iron produced is converted into alloys of iron.

State why alloys have more uses than pure metals.

An alloy of iron contains 0.40 % of molybdenum.

Calculate the mass of molybdenum contained in a 30 g sample of this alloy of iron.

mass of molybdenum =_........

Many transition metals are used to make the reactants in chemical cells.

Figure 8 shows a graph of the voltage produced by a chemical cell as it is used in a torch for many hours.

Suggest an explanation for the shape of the graph.

In a hydrogen-oxygen fuel cell, hydrogen and oxygen react at the electrodes.

The overall reaction occurring in this fuel cell is a reaction of hydrogen with oxygen.

Write the balanced equation for this reaction.

The electrodes of a fuel cell are in contact with water and air. The electrodes are made of platinum rather than iron.

State why iron is not a suitable metal for the electrodes of the cell.

Platinum acts as a catalyst.

State, in terms of its position in the periodic table, why you would expect platinum to act as a catalyst.

Some metal objects are electroplated.

State two reasons for electroplating a metal object.

Alloy steels are made when iron is alloyed with other transition metals such as cobalt and chromium.

Which row of the table shows the typical properties of a transition metal?

Figure 1 shows the chain on a bicycle.

Explain how lubricating the chain with oil prevents corrosion of the steel chain.

Iron fences can be galvanised by coating them with a layer of zinc. When the layer of zinc is scratched exposing the iron to the weather, the iron does not rust.

Explain why the exposed iron does not rust.

Metals have high melting points.

Explain, in terms of their structure and bonding, why metals have high melting points.